Which of the following components helps control rot in a utility pole?

The component that helps control rot in a utility pole is wood preservatives. These chemical treatments are applied to wooden utility poles to protect them against decay caused by fungi, insects, and other environmental factors. The use of wood preservatives significantly extends the lifespan of the poles, ensuring they remain structurally sound and safe for use over time.

Choosing metal caps does not specifically address the prevention of rot since their role is more about providing structural integrity at the top of the pole, helping to protect against elements like rain and snow. While crossarms and guy wires are essential for supporting and stabilizing the pole structure, they do not serve the function of preventing decay or rot. Thus, the application of wood preservatives is crucial in maintaining the longevity and functionality of utility poles.